<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>URL</title>
</head>
<body>
  <!-- 绝对路径 -->
  <a href="https://www.baidu.com">百度</a>
  <a href="//jd.com">京东</a>
  <a href="/search">搜索</a>
  <hr>
  <!-- 相对路径 -->
  <a href="./css/app.css">访问CSS</a>
  <a href="js/app.js">访问JS</a>
  <a href="../img/logo.png">访问图片</a>
  <a href="../../img/logo.png">访问图片</a>
</body>
</html>